Tuning Gate‐Opening of a Flexible Metal–Organic Framework for Ternary Gas Sieving Separation

Abstract

In comparison with the fast development of binary mixture separations, ternary mixture separations are significantly more difficult and have rarely been realized by a single material. Herein, a new strategy of tuning the gate‐opening pressure of flexible MOFs is developed to tackle such a challenge. As demonstrated by a flexible framework NTU‐65, the gate‐opening pressure of ethylene (C2H4), acetylene (C2H2), and carbon dioxide (CO2) can be regulated by temperature. Therefore, efficient sieving separation of this ternary mixture was realized. Under optimized temperature, NTU‐65 adsorbed a large amount of C2H2 and CO2 through gate‐opening and only negligible amount of C2H4. Breakthrough experiments demonstrated that this material can simultaneously capture C2H2 and CO2, yielding polymer‐grade (>99.99 %) C2H4 from single breakthrough separation.

Tuning Gate‐Opening of a Flexible Metal–Organic Framework for Ternary Gas Sieving Separation

“…f),g) Channels along aa xis and caxis with aperture size of 5.2 6.3 2 and 2.6 3.4 2 respectively.Cgray,Nblue, Fcyan, Si yellow. [27] Angewandte Chemie Forschungsartikel 22946 www.angewandte.de uptake of all three gases (Figure 2a), which is not promising for efficient separation of ternary mixture because the high C 2 H 4 uptake would result in significant amount of coadsorption of C 2 H 4 and low percentage of recycled C 2 H 4 . Since C 2 H 4 showed highest gate-opening pressure,i tisl ikely that at some temperature between 195 and 298 K, only C 2 H 2 and CO 2 can open the pore and be captured.…”

Molecular Sieving of Acetylene from Ethylene in a Rigid Ultra‐microporous Metal Organic Framework.

“…However, though quite low or negligible C 2 H 4 uptake is observed based on the adsorption data of single‐gas isotherms, co‐adsorption of C 2 H 2 and C 2 H 4 would still occur in dynamic gas mixture separation process once the closed or narrower pore system fully opened by C 2 H 2 (Figure 1). [20–21] Herein, we report an absolute molecular sieve of F−PYMO−Cu (F−pymo=5‐fluoro‐2‐hydroxypyrimidine) for C 2 H 2 /C 2 H 4 separation , which exhibited the regular 1D channels with pore size of 3.4 Å. Failed entrance of C 2 H 4 (kinetic diameter: 4.1 Å) into pore channel of F−PYMO−Cu was cooperatively evidenced by single‐gas sorption data of C 2 H 4 at 258/273/298 K and temperature‐programmed desorption data of saturated F−PYMO−Cu column after exposed to C 2 H 2 /C 2 H 4 gas mixture at 298 K. Thanks to the absolute molecular sieving effect and smaller kinetic diameter of CO 2 (3.3 Å) and C 2 H 2 (3.3 Å), C 2 H 4 with high purity of >99.9 % can be produced in one‐step from the binary mixture of C 2 H 2 /C 2 H 4 and the ternary mixture of C 2 H 2 /CO 2 /C 2 H 4 .…”

“…[14] Moreover, framework flexibility is also an unfavorable factor under this context because of co-adsorption behavior. Until now, there are six flexible MOFs (UTSA-300, [15] GeFSIX-14-Cu-i/ ZU-33, [16] NCU-100a, [17] bnn-1-CaÀ H 2 O, [18] GeFSIX-dps-Cu, [19] NTU-65 [20] ) reported showing the sieving effect for C 2 H 2 over C 2 H 4 by differential gate-opening behavior. However, though quite low or negligible C 2 H 4 uptake is observed based on the adsorption data of single-gas isotherms, co-adsorption of C 2 H 2 and C 2 H 4 would still occur in dynamic gas mixture separation process once the closed or narrower pore system fully opened by C 2 H 2 (Figure 1).…”

“…However, though quite low or negligible C 2 H 4 uptake is observed based on the adsorption data of single-gas isotherms, co-adsorption of C 2 H 2 and C 2 H 4 would still occur in dynamic gas mixture separation process once the closed or narrower pore system fully opened by C 2 H 2 (Figure 1). [20][21] Herein, we report an absolute molecular sieve of…”

Research Progress in Metal-Organic Framework and Its Composites for Separation of C2Based on Sieving Multiple Effects

“…柔性 MOF 材料 是在一定温度、压力、电信号等条件下, 通过骨架的收 缩和扩张调节孔窗尺寸, 可以选择性地只吸附一种气 体, 而对另一种气体分子则基本不吸附, 最终通过筛分 来实现气体混合物的高效分离 [58][59] . Li 等 [60] [60] Figure 6 Comparisons of adsorption isotherms for C 2 H 2 and C 2 H 4 on ELM-11 (a and b) and ELM-13 (c and d) at 273 and 298 K [60] 图 7 NTU-65 在不同温度时的 CO 2 、C 2 H 2 和 C 2 H 4 吸附等温线对比 [61] Figure 7 Comparisons of adsorption isotherms for CO 2 , C 2 H 2 and C 2 H 4 on NTU-65 at different temperatures [61] 化 学 学 报 [69] 化 学 学 报 和 C 2 H 6 (空心点)吸附等温线 [70] Figure 11 (a) Schematic diagrams of structure changes on UTSA-280 caused by H 2 O removal and NH 3 modified, (b) adsorption isotherms for C 2 H 4 (solid points) and C 2 H 6 (hollow points) on UTSA-280, UTSA-280-M1 and UTSA-280-M2 at 298 K [70] (4.69 mmol/g), 但其分离选择性仅为 2, 在工业化应用 存在一定的局限. 为了平衡吸附容量和分离选择性, Liao 等 [7] 合成了 具有一维微孔(0.33 nm×0.30 nm)金属多氮唑框架 MOF…”